The manufacturing process of a thin film transistor liquid crystal display (TFT-LCD) is complicated, which includes the procedures such as manufacturing an array substrate, manufacturing a color film substrate, performing cell alignment, and so on, resulting in a long manufacturing period. A light-emitting diode (LED), especially an organic light emitting diode (OLED), is a thin film electroluminescent device, which has the advantages including simple preparation process, low cost, high luminous efficiency, being easy to form a flexible structure, and the like. Therefore, the display technology that utilizes a light-emitting diode or an organic light-emitting diode has become an important display technology.